Minnesota River Fish Index of Biotic Integrity

[Scott M]

DNR electrofishing survey turns up variety of species, sizes

by John Cross

Mankato Free Press

September 16, 2012

When Chris Domeier, Doug Pierzina and Jeff Malzahn went fishing on the Minnesota River recently, there wasn’t a bait bucket or fishing pole to be found.

Still, whether they would catch any fish was never in doubt.

After motoring upstream, churning up a rooster tail of sand in the shallow water with the outboard, Domeier, the assistant manager at the Department of Natural Resources Ortonville Fisheries office, opened a hatch and yanked the starter rope off the generator stored there.

It clattered to life, reverberating through the hull of the aluminum boat as fisheries workers Pierzina and Malzahn worked at the bow, swinging two fiberglass poles each dangling a half-dozen electrodes away and into the water in front of them.

The bait of choice today would be about 250 volts of direct current.

“Any fish within about five feet of the electrodes will be temporarily stunned and when they drift to the surface and then netted,” he explained.

In a moment, Pierzina and Malzahn were dipping and scooping with long handled nets at the flashes of white as fish caught in the force field turned belly-up.

A multitude of minnow species, quillbacks, river carp, German carp, a few walleyes including a couple of dandy 24-inchers, channel catfish, striped bass, sheepshead, several shovelnose sturgeon, a couple of juvenile flathead catfish soon were sloshing in the livewell.

The DNR crew was surveying a 500-meter stretch of the Minnesota River between Redwood Falls and Morton.

During the last several weeks, DNR crews have been conducting similar electro-fishing surveys along 15 other stretches of the Minnesota river from Ortonville to the 35W bridge at Bloomington.

Until three of four years ago, the surveys were done on a less regular basis. More recently, the surveys intended to measure the health and diversity of the river’s fish populations have become an annual event.

“We now do them every year to get better data on the overall health of the fish populations,” he said.

By doing the surveys every year, he said, trends and patterns in fish populations can be more easily detected.

“Especially as we see more land-use changes, we’re trying the measure how those land-use changes affect the fishery in the river.”

The threat of invasive species such as the big-headed carp finding their way into Minnesota River system also is an added impetus to doing annual surveys.

“We haven’t seen any evidence of them yet,” he said.

With myriad species lurking in the stained river waters, traditional hook-and-line Minnesota River anglers are never quite sure what they might catch.

Likewise for the electro-fishermen.

Last week, dozens of species turned belly-up in the shallow water as the DNR crew attempted to negotiate the channel made shallow after months of drought.

Notably absent on this survey stretch, however, were the largest river predators - adult flathead catfish. Twenty-pound specimens are routinely caught by catfish anglers who pursue them with a passion. Thirty-pounders barely raised eyebrows in serious catfishing circles.

Several of the long-lived behemoths were captured at other sites during the surveys, however.

Local anglers will be interested to know that the largest flathead — a fifty-incher that was too big to weigh — was caught by the electro-fishing crew at the confluence of the Minnesota and Blue Earth Rivers at Mankato.

“Pretty close to a state record,” Domeier speculated.

One of the most unexpected catches - a braggin’-sized tiger muskie - also was netted by the crew, again at the Minnesota-Blue Earth River confluence.

Both were released and presumably still lurk in the area.

After being measured, weighed and checked for deformities, most of fish netted near Redwood Falls also were released.

However, some of the nicer specimens first would be making a temporary sidetrip to the Lac qui Parle County Fair to be displayed in the popular fish exhibit before being returned to the Minnesota River.

One of the biggest walleyes made the supreme sacrifice. It was slipped into a cooler to eventually be shipped to a St. Paul for testing for contamination levels.

That data would be plugged into the fish consumption guidelines issued annually by the Minnesota Department of Health.

“The catch today was s pretty typical mixture of species,” Domeier said, as the three men worked their way through some 70 fish, recording the data of every one, right down to the minnows.

After compiling the species, size and relative health of fish captured, the survey section is scored — the higher, the better.

Domeir said that the section of the river surveyed in Bloomington at the 35W bridge typically has received the highest score of the 16 river sections, mainly because of the numbers, diversity and health of the fish captured.

With all of the river sections surveyed, all that will remain will be compiling the numbers and comparing them with numbers gathered in earlier surveys.

“Over time, you can get a nice trend set of data and an idea of what’s going on out there,” Domeier said.

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[TruthWalleyes]

Thats awesome. Thanks for sharing. A 50" at the Blue Earth Confluence is pretty neat! That area has been heavily pressured this summer, but i doubt there has been too much pressure at night!

[aanderud]

Thanks for posting that, Scott.

[Gordie]

Thanks dachise that was a great read and those were some impressive fish they recorded. All those fish looked very healty too.

I remember a muskie that We caught near Jordan quite a few years ago but it was much,much smaller. I t was about 3.5 inches long and we caught it seining for bait by one of the creeks that flow into the river.

[DTro]

Sweet read!

A 50"er too big to be weighed??

[TruthWalleyes]

Sweet read!

A 50"er too big to be weighed??

I suppose it didn't fit in their 12"x12"x5" weighing pan

[Scott M]

If it's not a catfish assessment, they don't take out the big scales, IBI's are interested in presence/absence...the big guns are PVC halfpipes mounted on a scale with 40 kg top end.

[dan z]

Great post, good read!